Updating to iOS 5 Has Been A Massive Headache [Silicon Alley Insider]
The most significant upgrade is the launch of Apple's iCloud. The service provides iOS device users the ability to store iTunes music, photos, contacts, calendar on the cloud, with wireless synching. iOS 5 also offers enhanced notifications that pop up in a small bar at the top of the screen instead of a box in the middle of the screen that interrupts whatever app you're using at the time. The update also includes enhanced camera features, iMessage that improves upon iOS's text and media messaging, and a few new apps such as Newstand and Reminders.
Unfortunately, many users have encountered serious difficulty with the upgrade process. Multiple sources are reporting that they received error messages saying that the update couldn't be completed and the device could not be restored. The errors appear to have been caused by the massive amounts of people attempting to upgrade, flooding Apple's servers. It was reported that simply waiting a little while and trying again should result in a seamless upgrade.